Phylum: Charophyta Family: Desmidiaceae
Cosmarium contractum var. retusum (West & G.S. West) Krieger & Gerloff 1962
Cosmarium contractum is morphologically diverse and has created several varieties. There are also similarities with other species making identification sometimes difficult. It likes circumneutral waters such as loch-margins and pools. Because of the aforementioned identification difficulties, the status in the Outer Hebrides is uncertain
References:
Coesel, P.F.M. & Meesters, K.J. (2007) Mesotaeniaceae and Desmidiaceae of the European Lowlands
Kouwets, F.A.C. (1999) A check-list of desmids (Chlorophyta, Zygnemaphyceae) of France
Tsarenko, P.M., Wasser, S.P. & Nevo, E. editors (2014) Algae of Ukraine, Volume 4: Charophyta